The
human visual system is sensitive only to a small portion of the
electromagnetic spectrum. The visible spectrum ranges from about
400 to 700 nanometers. The wavelengths in the visible spectrum have
no intrinsic color; we perceive color as a result of interpretation
by our visual system. The lining of the eye, the retina, contains
light sensitive cells which detect specific, but somewhat overlapping,
ranges of the visible spectrum. The human eye can discern differences
between 8 and 12 million colors; however, we can reliably recall
and identify only 6 to 12 colors.